A Highly Integrated Wideband SIW Slot-Array Antenna With Surface Solder Balls in D Band

In this letter, a D-band 8 × 8 substrate integrated waveguide (SIW) slot array antenna with wideband and high integration based on high-density interconnect (HDI) technology is proposed. To achieve broadband, a novel series-fed 1 × 8 slot linear array configuration is investigated. Through the optimized radiating slot geometry, integration of parasitic patches, and redesigned feeding layer layout, the presented structure achieves significant enhancements in both impedance bandwidth (IMBW) and radiation performance. Furthermore, the introduced surface-welded solder balls, serving as a replacement for conventional metal fences, effectively improves the |S11| and gain flatness of the 8 × 8 array antenna. As a result, the antenna maintains excellent broadband characteristics even with half-wavelength spacing. Meanwhile, the antenna is manufactured using HDI technology, which further enhances the overall integration level of the antenna. Measured results demonstrate that the 8 × 8 slot array antenna achieves a -10 dB IMBW of 17.2% from 113 GHz to 134.6 GHz, a peak gain of 17.5 dBi at 120 GHz, a 3-dB gain bandwidth of 17%, and a 1-dB gain bandwidth of 13.8% from 115 GHz to 131.4 GHz.